1. Place potato pieces in a medium saucepan; cover with cold water to 2 inches above potatoes. Bring to a boil over medium-high heat. Reduce heat to medium, and gently simmer 10 minutes or until potatoes are tender. Drain potatoes.
2. Heat a small skillet over medium-high heat. Add 1 teaspoon oil to pan; swirl to coat. Add shallots to pan; sauté 3 minutes or until lightly browned, stirring occasionally. Remove from heat. Combine shallots, vinegar, mustard, lemon rind, lemon juice, salt, and black pepper in a small bowl, stirring well with a whisk. Gradually add remaining 2 tablespoons oil, stirring constantly with a whisk until combined. Drizzle dressing over warm potatoes; toss gently to coat. Cool completely.
3. Add arugula to potato mixture; toss gently. Serve immediately.